Dock levelers, also referred to as dock boards, are mounted in loading docks and are used to bridge the gap between the loading dock floor and the end of a vehicle parked at the loading dock. For example, trucks or tractor trailers may back into a loading dock for loading and unloading, and the dock leveler will form a bridge between the dock floor and the bed of the vehicle being serviced. The dock leveler enables material handling equipment, such as a forklift truck, and material handling personnel to move freely between the dock and the parked vehicle.
Typical dock levelers include a frame or support structure mounted in a recess in the dock known as a pit. A ramp, sometimes referred to as a deck, is generally pivoted about an upper end of the support structure between a horizontal, storage position and a working position where the deck may be rotated upwardly or downwardly to follow the height of a transport vehicle. Often, an extension lip movable between a downwardly hanging pendant position and an extended position is hinged to the forward end of the ramp to serve as an extension thereof.
The dock leveler pit is typically formed from concrete with structural steel angles or channels embedded in the exposed edges thereof, such as along the dock curb. The embedded angle at the rear of the pit (that is, the angle embedded along the rearmost dock floor curb, called the rear curb angle) is generally welded to the dock leveler frame to aid in anchoring the dock leveler in the pit. In this way, the frame can provide a path for vertical and horizontal loads borne by the deck and lip by passing the structural loads through the frame and into the floor and rear curb angle of the pit.
Pit floors, however, will generally not be level and square. For example, the floor of the pit may slope or undulate from front to back, from side to side, or both. To address this problem, extant dock leveler support structures are customarily designed to be shallower than the nominal pit depth, and typically use a stack of thin metal pieces known as shims inserted beneath the frame in order to stabilize the support structure in the pit, similar to how a matchbook or coaster may be used to stabilize a wobbly dining table. Shims are also used to raise the support structure until it is level with the rear curb angle of the dock leveler pit. Shims are typically sized to provide a structural path between the dock leveler and the pit floor, and are generally welded in place, both to each other and to the support frame.
Installing shims is difficult and time consuming, as it requires the installer to crawl under the dock leveler and apply laminations of shims to shore the support structure up to the pit floor. Failure to provide adequate shimming may leave the dock leveler hanging unsupported from the weld between the frame and the rear curb angle. This, in turn, can lead to structural failure of the frame or separation of the dock leveler from the rear curb angle when loaded. Even where adequate shimming is provided to level and stabilize the dock leveler, if the shims are improperly welded, or not welded at all, vibrations suffered during use may induce the shims to “walk” out from under the frame, causing a similarly undesirable condition.
Accordingly, it is desirable to provide a dock leveler support frame that stabilizes and levels the dock leveler, and provides structural support for and a load path between the deck and the pit, without the need to install shimming or access the underside of the support frame during installation.